1. Field of the Invention
This invention relates to the field of motor vehicles, and more particularly, to a system and method for providing interior illumination in a motor vehicle.
2. Related Art
Motor vehicles generally provide some kind of interior illumination or lighting. Interior lighting can be provided to a number of different locations and can be used to illuminate different components and systems associated with the interior of a motor vehicle. Some examples of interior illumination include a dome light and a map light. Dome lights generally provide illumination to most of the passenger cabin. This can assist drivers and occupants in entering or exiting a motor vehicle at night time. Map lights can provide directed illumination to assist in reading maps or directions. Unlike dome lights, map lights can be designed to operate while the motor vehicle is in motion.
Other components are also illuminated to assist with visibility during low light conditions. Low light conditions include night time, dawn, dusk and low light conditions caused by objects that obstruct sunlight. Examples of obstructions include trees, woods, bridges, buildings and tunnels. In some cases, certain components are illuminated to assist with their visibility during low light conditions. Some examples of components that are illuminated include switches, the dashboard, the instrument cluster and the center console. These components can be back lit, directly lit or these components can include elements that illuminate like LCD's or LED's.
Various lighting control systems have been proposed. U.S. Pat. No. 5,583,484 to Asano discloses a lighting control apparatus on a control panel in an automobile including brightness control means responsive to an operation of a dimmer knob for giving brightness setting information, for giving a brightness signal for controlling a luminosity of an instrument panel, and for giving a luminosity of the control panel, which is provided near the instrument panel to a luminosity corresponding to the operation of the dimmer knob.
U.S. Patent Application No. 2003/0214242 to Berg-Johansen discloses a system for controlling light including a display readable in fall daylight conditions as well as at the other extreme, in complete darkness. Sudden changes in the interior cockpit lighting conditions may occur, such as when the general cockpit lighting is turned on or off or when clouds block direct sunlight. An appropriate amount of backlight illumination is required to ensure consistent, readable avionics displays under a variety of changing lighting conditions.
Japanese Patent Number 4143134 to Takesato and assigned to Mazda, discloses lighting for appliances such as liquid crystals and fluorescent lamps provided for the instrument panel and its peripheries of a vehicle. The lighting appliances are dimmed by dimming commands from a dimming circuit which is operated with both a switch in a small lamp system and a head lamp switch turned on. A dimming adjust circuit is interposed within a control unit and sends a mode signal to the dimming circuit in response to an input from a sunshine sensor so the degree of dimming can be adjusted in response to external brightness.
While the proposed lighting systems discussed above include some features; none of the proposed lighting control systems provides a system that can rapidly respond to sudden changes in ambient lighting conditions, prevents flicker, or offers a continuously variable dimming system. There is currently a need for a system that improves the visibility of interior elements by addressing the noted shortcomings.